Liquid crystal display device

ABSTRACT

A liquid crystal display device includes dual bank type source driver PCBs installed at the top and the bottom of a liquid crystal panel, a gate driver PCB, and a staple-shaped main PCB formed in a body with a top portion and a bottom portion proceeding in the horizontal direction and a side portion proceeding in the vertical direction. The top portion and the bottom portion of the main PCB axially meet the side portion of the main PCB at a predetermined angle. A timing controller is mounted at the main PCB to process signals input from outside and generate driving signals. The main PCB transmits the relevant driving signals to the respective source driver PCBs and the gate driver PCB.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a Continuation Application of U.S. patentapplication Ser. No. 09/933,178 filed on Aug. 21, 2001 now U.S. Pat. No.6,867,758, which claims priority to and the benefit of Korean PatentApplication No. 2000-70084 filed on Nov. 23, 2000, which are herebyincorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a liquid crystal display device and,more particularly, to a liquid crystal display device which is providedwith a printed circuit board (PCB) module adapted for a wide screen andhigh resolution device.

(b) Description of the Related Art

Generally, a liquid crystal display device includes a liquid crystaldisplay module with a liquid crystal panel where liquid crystal cellsare arranged between two glass substrates in a matrix form, and abacklight unit installed at the rear of the liquid crystal panel, a PCBmodule installed at the rear of the backlight unit to drive the liquidcrystal panel, and a case covering the liquid crystal display module andthe PCB module to protect them. The PCB module is a driving circuit thatreceives picture data of red (R), green (G) and blue (B) andsynchronization signals from outside, and processes them to generatepicture signals, scanning signals and timing control signals. The PCBmodule transmits the generated signals to the liquid crystal panel suchthat the latter can display the desired images in a stable manner. Sucha PCB module is provided with a plurality of PCBs, and flexible printedcables (FPCs) interconnecting the PCBs for signal transmission.

FIG. 1 is a block diagram illustrating the circuit structure of a liquidcrystal display device according to a prior art. As shown in FIG. 1, thePCB module for a display device bearing relatively lower resolution ofSVGA (600*800) includes a main PCB 10, a gate driver PCB 20, and asource driver PCB 30 or 40. The main PCB 10 receives picture data of R,G and B and synchronization signals from the outside, and processes themby way of a timing controller (T-con) such that they are adapted for thestructure of a liquid crystal panel 50. The timing controller is acustom IC in the form of a flat pin grid array (FPGA).

Gate driver IC tape automated bonds (TABs) are attached to the gatedriver PCB 20 to receive gate driver control signals 60 and 61 from themain PCB 10, and to supply scanning signals to the liquid crystal panel50 based on the received control signals 60 and 61. Source driver ICTABs are attached to the source driver PCB 30 or 40 to receive sourcedriver control signals 70 and 71 from the main PCB 10, and to supplypicture signals to the liquid crystal panel 50 based on the receivedcontrol signals 70 and 71.

The PCB module further includes an FPC for transmitting the gate drivercontrol signals 60 and 61 from the main PCB 10 to the gate driver PCB20, and an FPC for transmitting the source driver control signals 70 and71 from the main PCB 10 to the source driver PCB 30 or 40. In case themain PCB 10 is separated into two or more portions, other FPCs may beprovided to interconnect the separated portions of the main PCB 10.

As the liquid crystal display device has been developed to bear a widescreen and a high resolution of XGA (768*1024), SXGA (1024*1280), orUXGA (1200*1600), a dual bank type PCB module is mainly used for such adisplay device because of the narrow width of data lines placed at abottom substrate of the liquid crystal panel 50 and the space for driverIC TABS. The dual bank type PCB also allows a partitioned driving thatenables high speed data processing. In the dual bank type PCB module,two source driver PCBs are installed at the rear of the liquid crystalpanel 50 to supply picture signals from the top and the bottom.

FIGS. 2 and 3 illustrate the structure of a dual bank type PCB modulefor a liquid crystal display device, respectively.

As shown in FIG. 2, source driver PCBs 110 and 120 are installed at therear of a liquid crystal display module 100 such that they are connectedto an I-shaped main PCB 140 via FPCs 150 and 170, respectively. A gatedriver PCB 130 is connected to the main PCB 140 via an FPC 160 side byside. The main PCB 140 has a timing controller to generate various kindsof data and control signals, and supply them to the source driver PCBs110 and 120 and the gate driver PCB 130 via the FPCs 150, 160 and 170.

As shown in FIG. 3, source driver PCBs 210 and 220 are installed at therear of a liquid crystal display module 200 such that they are connectedto three main PCBs 240, 241 and 242 via FPCs 250 and 280, respectively.A gate driver PCB 230 is connected to the main PCB 240 via an FPC 290side by side. The main PCBs 240, 241 and 242 are provided with a timingcontroller to generate various kinds of data signals and controlsignals, and supply them to the source driver PCBs 210 and 220 and thegate driver PCB 230 via the FPCs 250, 260, 270, 280 and 290.

However, in the usual dual bank type PCB module shown in FIG. 2, thetransmission of the picture data is delayed at the right screen portionwhen viewed from the front side so that normal display cannot be made.In order to overcome such a problem, as shown in FIG. 3, it is proposedthat three separate main PCBs 240, 241 and 242 should be introduced andinterconnected via two FPCs 260 and 270. A space for mounting driver ICTABs, signal lines, resistors and condensers is provided at the sourcedriver PCBs 210 and 220, and the main PCBs 240, 241 and 242 are designedin consideration of intersignal coupling, noise, and electromagneticinterference (EMI) such that the required signal transmission can bemade within the range of tolerance. However, even in such a structure,signal delay or distortion tends to generate due to the delay factorintrinsic to resistance capacitance (RC) from interconnecting the PCBsby the FPCs 260 and 270. The RC may accrue to the combination resistanceof the PCB connector and the FPC connector, and other parasiticcapacitance. Consequently, the signals applied to the source driver PCBs210 and 220 are not timing-controlled in a stable manner so that settingand holding of the picture data become to be inappropriate fordisplaying, resulting in serious display failure accompanied with screennoise and line defect.

Meanwhile, the usual liquid crystal display screen is formed in arectangular shape where the ratio of the horizontal length to thevertical length is 4:3, or 16:9. However, in near future, it is expectedthat the display screen for medical equipment and radar where screensize and resolution become bigger and higher with a longer verticallength may be required in a square shape. Accordingly, the number ofhorizontal lines per frame increases in signal processing. Hence, onehorizontal synchronization signal cycle becomes shorter to reduce theperiod of time for processing the picture data. This decreases timingmargin. In this respect, it is required to develop a technique thatprocesses the picture data within the range of signal delay anddistortion tolerance, while preventing screen noise, coupling, and EMI.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a liquid crystaldisplay device that can reduce signal delay and distortion in driving aliquid crystal panel having a wide screen and a high resolution.

This and other objects may be achieved by a liquid crystal displaydevice with the following features.

The liquid crystal display device includes dual bank type source driverPCBs installed at the top and the bottom of a liquid crystal panel, agate driver PCB, and a staple-shaped main PCB formed in a body with topand bottom portions proceeding in the horizontal direction and a sideportion proceeding in the vertical direction. The top and the bottomportions of the main PCB axially meet the side portion of the main PCBat a predetermined angle. A timing controller is mounted at the main PCBto process signals input from the outside and generate driving signals.The main PCB transmits the relevant driving signals to the respectivesource driver PCBs and the gate driver PCB.

The top and bottom portions of the main PCB axially meet the sideportion of the main PCB substantially at a right angle. Alternatively,the top and the bottom portions of the staple-shaped main PCB mayaxially meet the side portion of the main PCB at an acute angle, or anobtuse angle. The top and bottom portions of the staple-shaped main PCBhave an axial length of one half or more of the liquid crystal panel.

The respective top and bottom portions of the staple-shaped main PCB areconnected to the corresponding source driver PCBs via one or more FPCsto transmit the relevant driving signals to the source driver PCBs.

The side portion of the staple-shaped main PCB is connected to the gatedriver PCB via one or more FPCs to transmit the relevant driving signalsto the gate driver PCB. The timing controller is positioned at the sideportion of the staple-shaped main PCB.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which likereference symbols indicate the same or the similar components, wherein:

FIG. 1 is a block diagram illustrating the circuit structure of a liquidcrystal display according to a prior art;

FIG. 2 is a block diagram of a PCB module for the liquid crystal displaydevice shown in FIG. 1;

FIG. 3 is a block diagram of another PCB module for the liquid crystaldisplay device shown in FIG. 1;

FIG. 4 is a block diagram of a PCB module for a liquid crystal displaydevice according to a preferred embodiment of the present invention;

FIG. 5 illustrates an arrangement of picture data supplied from sourcedrivers of the PCB module shown in FIG. 4; and

FIG. 6 illustrates a way of partitioning a liquid crystal panel for theliquid crystal display device shown in FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of this invention will be explained with referenceto the accompanying drawings.

FIG. 4 is a block diagram of a liquid crystal display device accordingto a preferred embodiment of the present invention.

As shown in FIG. 4, the liquid crystal display device includes a liquidcrystal display module 300, a staple-shaped main PCB 340, first andsecond source driver PCBs 310 and 320 installed at the rear of theliquid crystal display module 300 up and down such that they areconnected to the main PCB 340 via first, second, third and fourth sourceFPCs 350, 360, 370 and 380, and a gate driver PCB 330 connected to themain PCB 340 via gate FPCs 390 and 400 side by side. The main PCB 340generates various kinds of data signals and control signals, andsupplies them to the source driver PCBs 310 and 320 and the gate driverPCB 330 via the FPCs 350, 360, 370, 380, 390 and 400.

The liquid crystal module 300 includes a liquid crystal panel whereliquid crystal cells are arranged between two glass substrates in amatrix form, and a backlight unit installed at the rear of the liquidcrystal panel.

Source driver IC TABs are attached to the first source driver PCB 310 toreceive driving signals from the main PCB 340, and to supply picturedata to the corresponding pixels of the liquid crystal panel based onthe received driving signals. How to correspond the pixels with thepicture data depends upon the ways of driving. For instance, if thepixels are driven in a double-partitioned way, the corresponding pixelsmay be the odd-numbed pixels from the left on the horizontal axis of theliquid crystal panel. As shown in FIG. 6, if the pixels are driven in aquadruple-partitioned way, the corresponding pixels may be the pixelspositioned at the top portions A and B of the liquid crystal panel.

Source driver IC TABs are also attached to the second source driver PCB320 to receive driving signals from the main PCB 340, and to supplypicture data to the corresponding pixels of the liquid crystal panelbased on the received driving signals. How to correspond the pixels withthe picture data depends upon the ways of driving. For instance, if thepixels are driven in a double-partitioned way, the corresponding pixelsmay be the even-numbed pixels from the left on the horizontal axis ofthe liquid crystal panel. As shown in FIG. 6, in case the pixels aredriven in a quadruple-partitioned way, the corresponding pixels may bethe pixels positioned at the bottom portions C and D of the liquidcrystal panel.

Gate driver IC TABs are attached to the gate driver PCB 330 to receivegate driver control signals from the main PCB 340, and to supplyscanning signals to the liquid crystal panel based on the receivedcontrol signals.

A timing controller is provided at the main PCB 340 to process the inputsignals from outside and to generate driving signals. The drivingsignals are supplied to the first source driver PCB 310, the secondsource driver PCB 320, and the gate driver PCB 330. The main PCB 340 isformed in a body without any interconnection cable such as FPC whilebearing a staple shape of “⊂” or “⊃” when viewed either in the displaydirection or the other way. That is, the main PCB 340 has top and bottomportions proceeding in the horizontal direction, and a side portionproceeding in the vertical direction. The top and bottom portions of themain PCB 340 axially meet the side portion thereof at a right angle, orat an acute or obtuse angle. The first source FPC 350 and the secondsource FPC 360 are flexible cables that transmit picture data andvarious kinds of control signals from the main PCB 340 to the firstsource driver PCB 310 to drive the source driver IC TABs attachedthereto. As shown in FIG. 6, if the liquid crystal panel is driven in aquadruple-partitioned way, the first source FPC 350 transmits thepicture data and control signals generated from the main PCB 340 to thefirst source driver PCB 310 to drive the source driver IC TABcorresponding to the A portion of the liquid crystal panel. The secondsource FPC 360 transmits the picture data and control signals generatedfrom the main PCB 340 to the first source driver PCB 310 to drive thesource driver IC TAB corresponding to the B portion of the liquidcrystal panel.

The third source FPC 370 and the fourth source FPC 380 are flexiblecables that transmit picture data and various kinds of control signalsfrom the main PCB 340 to the second source driver PCB 320 to drive thesource driver IC TABs attached thereto. As shown in FIG. 6, if theliquid crystal panel is driven in a quadruple-partitioned way, the thirdsource FPC 370 transmits the picture data and control signals generatedfrom the main PCB 340 to the second source driver PCB 320 to drive thesource driver IC TAB corresponding to the C portion of the liquidcrystal panel. The fourth source FPC 380 transmits the picture data andcontrol signals generated from the main PCB 340 to the second sourcedriver PCB 320 to drive the source driver IC TAB corresponding to the Dportion of the liquid crystal panel.

The first gate FPC 390 and the second gate FPC 400 are flexible cablesthat transmit power and various kinds of control signals from the mainPCB 340 to the gate driver PCB 330 to drive the gate driver IC TABsattached thereto. As shown in FIG. 6, if the liquid crystal panel isdriven in a quadruple-partitioned way, the first gate FPC 390 transmitsthe power and control signals generated from the main PCB 340 to thegate driver PCB 330 to drive the gate driver IC TAB corresponding to theA and B portions of the liquid crystal panel. The second gate FPC 400transmits the power and control signals generated from the main PCB 340to the gate driver PCB 330 to drive the gate driver IC TAB correspondingto the C and D portions of the liquid crystal panel.

In operation, upon receipt of input signals from outside, the main PCB340 processes the input signals by way of a built-in timing controller,and generates picture data and various kinds of control signals. Themain PCB 340 transmits part of the picture data and control signals tothe first source driver PCB 310 via the first and second source FPCs 350and 360 while transmitting part of the picture data and control signalsto the second source driver PCB 320 via the third and fourth source FPCs370 and 380. The main PCB 340 generates power and various kinds ofcontrol signals for driving gate driver IC TABs attached to the gatedriver PCB 330, and transmits them to the gate driver PCB 330 via thefirst and second gate FPCs 390 and 400.

When the liquid crystal panel is driven in a double-partitioned way, theodd-numbered picture data R_(2n−1), G_(2n) and B_(2n−1) generated at themain PCB 340 are transmitted to the first source driver PCB 310 via thefirst and second source FPCs 350 and 360. And the even-numbered picturedata R_(2n), G_(2n−1) and B_(2n) are transmitted to the second sourcedriver PCB 320 via the third and fourth FPCs 370 and 380. FIG. 5illustrates the sequence of displaying picture data at the pixels of theliquid crystal panel.

By contrast, as shown in FIG. 6, if the liquid crystal panel is drivenin a quadruple-partitioned way, the first source FPC 350 transmits thepicture data and control signals generated from the main PCB 340 to thefirst source driver PCB 310 to drive the source driver IC TABcorresponding to the A portion of the liquid crystal panel. The secondsource FPC 360 transmits the picture data and control signals generatedfrom the main PCB 340 to the first source driver PCB 310 to drive thesource driver IC TAB corresponding to the B portion of the liquidcrystal panel. The third source FPC 370 transmits the picture data andcontrol signals generated from the main PCB 340 to the second sourcedriver PCB 320 to drive the source driver IC TAB corresponding to the Cportion of the liquid crystal panel. The fourth source FPC 380 transmitsthe picture data and control signals generated from the main PCB 340 tothe second source driver PCB 320 to drive the source driver IC TABcorresponding to the D portion of the liquid crystal panel. Furthermore,the first gate FPC 390 transmits the power and control signals generatedfrom the main PCB 340 to the gate driver PCB 330 to drive the gatedriver IC TAB corresponding to the A and B portions of the liquidcrystal panel. The second gate FPC 400 transmits the power and controlsignals generated from the main PCB 340 to the gate driver PCB 330 todrive the gate driver IC TAB corresponding to the C and D portions ofthe liquid crystal panel.

The main PCB 340 is connected to the first source driver PCB 310 via thefirst and second source FPCs 350 and 360 while being connected to thesecond source driver PCB 320 via the third and fourth FPCs 370 and 380.It is such structured to supply picture data without signal delay in theliquid crystal panel with a screen size of 20 inch or more, and a highresolution.

As described earlier, even in the configuration of the main PCBs 240,241 and 242 as shown in FIG. 3, signal delay or distortion tends togenerate due to the delay factor intrinsic to the RC by interconnectingthe PCBs with the FPCs 260 and 270. Consequently, the signals applied tothe source driver PCBs 210 and 220 are not controlled timely in a stablemanner. This sets and holds the picture data inappropriately fordisplaying, resulting in serious display failure as well as screennoises and line defects.

In view of such a problem, the main PCB 340 is formed in a staple shapeto be connected to the first source driver PCB 310 via the first andsecond source FPCs 350 and 360 while being connected to the secondsource driver PCB 320 via the third and fourth FPCs 370 and 380.Furthermore, the main PCB 340 is designed considering intersignalcoupling, noise and EMI, Thus, signals can be supplied within thetolerance range of the source driver PCBs 310 and 320.

Particularly, in a quadruple-partitioned way driving, the problems ofintersignal coupling, noise and EMI become more amplified. That is, inthe top area of the liquid crystal panel, the source driver IC TABsattached to the source driver PCB 310 differ in driving the A portionand the B portion of the liquid crystal panel. And the number of signallines for transmitting the different picture data and control signals tothe respective IC TABs amounts to several tens of lines. Similarly, inthe bottom area of the liquid crystal panel, the source driver IC TABsfor driving the C portion and the D portion of the liquid crystaldisplay panel are also different, and the number of signal lines forsupplying the different picture data and control signals amounts toseveral tens of lines. Therefore, it is necessary that the main PCB 340should be connected to the first source driver PCB 310 via the first andsecond source FPCs 350 and 360 while being connected to the secondsource driver PCB 320 via the third and fourth FPCs 370 and 380. In thisstructure, the main PCB 340 can supply signals within the tolerancerange of the source driver PCBs 310 and 320. Furthermore, the sourcedriver PCBs 310 and 320 are structured to have a sufficient space forreceiving the driver IC TABs, the signal lines, and resistors orcondensers for giving bias to the respective signal voltages in anappropriate manner.

The top and bottom portions of the staple-shaped main PCB 340 have anaxial length amounting to one half or more of the liquid crystal panel.The second source FPC 360 and the fourth source FPC 380 interconnectingthe first and second source driver PCBs 310 and 320 are positioned atthe area that is less than one half of the entire axial length of thetop and bottom portions of the main PCB 340 from the side portionthereof. The first source FPC 350 and the third source FPC 370interconnecting the first and second source driver PCBs 310 and 320 arepositioned at the area that is one half or more of the entire axiallength of the top and bottom portions of the main PCB 340 from the sideportion thereof. In this structure, the possible problems of intersignalcoupling, noise, and EMI can be prevented in an efficient manner.

As described above, in driving a liquid crystal panel with a dual banktype PCB module in a double or quadruple-partitioned way, thestaple-shaped main PCB 340 minimizes signal delay and distortion whilepreventing the possible problems of intersignal coupling, noise, and EMIin an efficient manner. Accordingly, such a main PCB can be well adaptedfor driving 20 inch or larger high resolution liquid crystal panels aswell as square-shaped liquid crystal panels.

While the present invention has been described in detail with referenceto the preferred embodiments, those skilled in the art will appreciatethat various modifications and substitutions can be made thereto withoutdeparting from the spirit and scope of the present invention as setforth in the appended claims.

1. A liquid crystal display (LCD), comprising: a main printed circuitboard (PCB) including a first portion extending in a first direction, asecond portion extending in the first direction, and a third portionextending in a second direction and bridging the first portion and thesecond portion; a first source driver PCB arranged close to the firstportion of the main PCB that has an axial length at least one half ofthe first source driver PCB; a second source driver PCB arranged closeto the second portion of the main PCB that has an axial length at leastone half of the second source driver PCB; first, second, third, andfourth source cables, wherein the first and third source cables connectthe first and second portions of the main PCB with the first and secondsource driver PCB, respectively, and are positioned at locations thatare one half or more of the entire axial length of the first and secondportions of the main PCB from the third portion thereof, and wherein thesecond and fourth source cables connect the first and second portions ofthe main PCB, respectively and are positioned at locations that are lessthan one half of the entire axial length of the first and secondportions of the main PCB from the third portion thereof; a gate driverPCB; a first gate driver cable connected between the main PCB and thegate driver PCB; and a second gate driver cable connected between themain PCB and the gate driver PCB.
 2. The LCD of claim 1, wherein thefirst direction is perpendicular to the second direction.
 3. The LCD ofclaim 1, where the main PCB further comprises a timing controllermounted on the third portion and generating a gate driving signal, afirst source driving signal and a second source driving signal.
 4. TheLCD of claim 1, wherein the third source cable and the fourth sourcecable are flexible printed cables (FPCs).
 5. The LCD of claim 1, whereinthe first source cable and the second source cable are flexible printedcables (FPCs).
 6. A liquid crystal display (LCD), comprising: a liquiddisplay panel divided into a plurality of partitions arranged in amatrix including a plurality of rows and a plurality columns; a mainprinted circuit board (PCB) including a first portion extending in afirst direction, a second portion extending in the first direction, anda third portion extending in a second direction and bridging the firstportion and the second portion; a first source driver PCB arranged closeto the first portion of the main PCB that has an axial length at leastone half of the first source driver PCB; a second source driver PCBarranged close to the second portion of the main PCB that has an axiallength at least one half of the second source driver PCB; first, second,third, and fourth source cables, wherein the first and third sourcecables connect the first and second portions of the main PCB with thefirst and second source driver PCB, respectively, and are positioned atlocations that are one half or more of the entire axial length of thefirst and second portions of the main PCB from the third portionthereof, and wherein the second and fourth source cables connect thefirst and second portions of the main PCB, respectively and arepositioned at locations that are less than one half of the entire axiallength of the first and second portions of the main PCB from the thirdportion thereof; a gate driver PCB; and a plurality of gate drivercables coupled between the third portion of the main PCB and the gatedriver PCB, each gate driver cable transferring a signal for thecorresponding partition.
 7. A liquid crystal display (LCD), comprising:a main printed circuit board (PCB) including a first portion extendingin a first direction, a second portion extending in the first direction,and a third portion extending in a second direction and bridging thefirst portion and the second portion; a first source driver PCB arrangedclose to the first portion of the main PCB that has an axial length atleast one half of the first source driver PCB; a second source driverPCB arranged close to the second portion of the main PCB that has anaxial length at least one half of the second source driver PCB; first,second, third, and fourth source cables, wherein the first and thirdsource cables connect the first and second portions of the main PCB withthe first and second source driver PCB, respectively, and are positionedat locations that are one half or more of the entire axial length of thefirst and second portions of the main PCB from the third portionthereof, and wherein the second and fourth source cables connect thefirst and second portions of the main PCB, respectively and arepositioned at locations that are less than one half of the entire axiallength of the first and second portions of the main PCB from the thirdportion thereof; a gate driver PCB; and a plurality of cables connectedbetween the main PCB and the gate driver PCB.